Dr. Oakley wields a wicked tranquilizer gun but points out that the needle doesn't always stick or inject. Like that show. Also, the musk ox run around quite a bit before going down.
Anyway, the proponents of this technique of leg shooting might watch the interview with the female NYPD officer who helps that little 4 year old with a TQ and sprint to to the ambulance. She pointed out in an interview that leg shots were very dangerous due to the blood vessels that could quickly bleed you out.